One]Cross Citation with Related Applications [2]This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0091148 dated July 26, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification. [3] technical field [4] The present invention relates to a composite anode active material, a method for manufacturing the same, an anode including the same, and a secondary battery. background [5] Recently, with the rapid spread of electronic devices using batteries, such as mobile phones, notebook computers, and electric vehicles, the demand for small, lightweight and relatively high-capacity secondary batteries is rapidly increasing. In particular, a lithium secondary battery has been in the spotlight as a driving power source for a portable device because it is lightweight and has a high energy density. Accordingly, research and development efforts for improving the performance of lithium secondary batteries are being actively conducted. [6] In general, a lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, an electrolyte, an organic solvent, and the like. In addition, the positive electrode and the negative electrode may have an active material layer including a positive electrode active material or a negative electrode active material on a current collector. Generally, lithium-containing metal oxides such as LiCoO 2 and LiMn 2 O 4 are used for the positive electrode as a positive electrode active material. Accordingly, a carbon-based active material and a silicon-based negative active material that do not contain lithium are used as the negative electrode active material for the negative electrode. [7] In particular, among the negative active materials, silicon-based negative active materials are attracting attention in that they have about 10 times higher capacity than carbon-based negative active materials, and due to their high capacity, high energy density can be realized even with thin electrodes. However, the silicon-based negative active material has not been widely used due to the problem of volume expansion due to charging and discharging, cracking/damage of the active material particles, and deterioration of the lifespan properties thereof. [8] In particular, the silicon-based negative active material has problems in that the distance between the active materials increases and an electrical short occurs due to volume expansion/contraction due to charging and discharging, and accordingly, the passage of charge is lost and lithium ions are isolated, thereby reducing the capacity and Lifespan deterioration can be accelerated. [9] Therefore, there is a need for the development of a secondary battery capable of improving the lifespan characteristics while realizing the high capacity and energy density of the silicon-based anode active material. [10] Korean Patent Laid-Open No. 10-2017-0074030 relates to a negative active material for a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery including the same, and discloses a negative active material including a porous silicon-carbon composite. There is a limit to solving it. [11] [Prior art literature] [12] [Patent Literature] [13] Korean Patent Publication No. 10-2017-0074030 DETAILED DESCRIPTION OF THE INVENTION technical challenge [14] One object of the present invention is to provide a composite anode active material capable of effectively preventing an electrical short circuit between active materials due to charging and discharging when using a silicon-based active material and improving lifespan characteristics. [15] In addition, another object of the present invention is to provide a method for manufacturing the above-described composite negative active material. [16] In addition, another object of the present invention is to provide a negative electrode and a secondary battery including the above-described composite negative electrode active material. means of solving the problem [17] The present invention is a silicon-based core particle; an outer carbon coating layer formed on the silicon-based core particles; and a single-walled carbon nanotube; wherein the single-walled carbon nanotube is in contact with the outer carbon coating layer, wherein a portion of the body of the single-walled carbon nanotube is spaced apart from the outer carbon coating layer, and the outer carbon coating layer It provides a composite anode active material containing silver oxygen in an amount of 35 wt% to 55 wt% in the outer carbon coating layer. [18] In addition, the present invention comprises the steps of mixing silicon-based core particles, a precursor for forming an outer carbon coating layer, and single-walled carbon nanotubes; and heat-treating the mixture at 250°C to 650°C. [19] In addition, the present invention is a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, wherein the negative electrode active material layer provides a negative electrode including a negative electrode material including the above-described composite negative active material, a binder, and a conductive material. [20] In addition, the present invention is the above-described negative electrode; an anode opposite to the cathode; a separator interposed between the negative electrode and the positive electrode; and an electrolyte; provides a secondary battery comprising. Effects of the Invention [21] The composite anode active material of the present invention includes a silicon-based core particle, an outer carbon coating layer formed on the silicon-based core particle, and a single-walled carbon nanotube, wherein the single-walled carbon nanotube is in contact with the outer carbon coating layer, the single-wall A portion of the body of the carbon nanotube is spaced apart from the outer carbon coating layer, and the outer carbon coating layer contains oxygen in a specific content. A portion of the single-walled carbon nanotube is attached to the outer carbon coating layer, and the remaining portion that is not attached is spaced apart from the outer carbon coating layer and exposed to the outside of the composite anode active material to form a conductive network to prevent electrical short between active materials. Therefore, even when volume expansion/contraction occurs due to charging and discharging of the active material, an electrical short circuit between the active materials can be prevented. In addition, since the single-walled carbon nanotube is partially attached to and fixed to the outer carbon coating layer, a conductive network can be uniformly and stably formed in the negative electrode, thereby improving the lifespan characteristics of the negative electrode and the secondary battery. [22] In addition, according to the manufacturing method of the composite negative electrode active material of the present invention, the composite negative electrode active material is prepared by mixing silicon-based core particles, a precursor for forming an outer carbon coating layer, and single-walled carbon nanotubes, and then complexing them in a specific temperature range. Accordingly, by preventing carbonization of the carbon coating layer due to heat treatment at an excessively high temperature, the single-walled carbon nanotubes may be partially attached to the carbon coating layer at an appropriate level, and may preferably contribute to the formation of a conductive network between active materials. Brief description of the drawing [23] 1 is a photograph of the composite negative active material of Example 1 observed with a scanning electron microscope (SEM). [24] 2 is a photograph of the composite negative active material of Example 2 observed with a scanning electron microscope (SEM). [25] 3 is a photograph of the composite negative active material of Comparative Example 1 observed with a scanning electron microscope (SEM). [26] 4 is a photograph of the composite negative active material of Comparative Example 2 observed with a scanning electron microscope (SEM). [27] 5 is a photograph of the composite negative active material of Comparative Example 4 observed with a scanning electron microscope (SEM). Modes for carrying out the invention [28] The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention. [29] The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. [30] In the present specification, terms such as "comprise", "comprising" or "have" are intended to designate the presence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that the existence or addition of numbers, steps, elements, or combinations thereof, is not precluded in advance. [31] In the present specification, the average particle diameter (D 50 ) may be defined as a particle diameter corresponding to 50% of the cumulative volume in the particle size distribution curve of the particles. The average particle diameter (D 50 ) may be measured using, for example, a laser diffraction method. In general, the laser diffraction method can measure a particle diameter of several mm from a submicron region, and can obtain results of high reproducibility and high resolution. [32] Hereinafter, the present invention will be specifically described. [33] [34] [35] The present invention relates to a composite anode active material. The composite negative active material may be preferably used in a lithium secondary battery. [36] The composite anode active material of the present invention includes silicon-based core particles; an outer carbon coating layer formed on the silicon-based core particles; and a single-walled carbon nanotube; wherein the single-walled carbon nanotube is in contact with the outer carbon coating layer, wherein a portion of the body of the single-walled carbon nanotube is spaced apart from the outer carbon coating layer, and the outer carbon coating layer Silver contains oxygen in an amount of 35 wt% to 55 wt% in the outer carbon coating layer. [37] In general, silicon-based anode active materials are known to have about 10 times higher capacity than carbon-based active materials. Accordingly, when silicon-based anode active materials are applied to anodes, thin-film electrodes having a high level of energy density even with a thin thickness are difficult to achieve. is expected to be possible. However, the silicon-based negative active material has a problem of deterioration in lifespan due to volume expansion/contraction according to insertion/desorption of lithium according to charging and discharging. In particular, when the silicon-based active material undergoes volume expansion/contraction due to charging and discharging, electrical contact deteriorates due to an increase in the distance between the active materials and an electrical short circuit occurs, which results in loss of the passage of charge and isolation of lithium ions. This may cause rapid deterioration of the lifespan of the anode and decrease in capacity. [38] In order to solve this problem, the composite anode active material of the present invention includes a silicon-based core particle, an outer carbon coating layer formed on the silicon-based core particle, and a single-wall carbon nanotube (hereinafter referred to as SWCNT), and the SWCNTs are in contact with the outer carbon coating layer, but a portion of the SWCNT body is spaced apart from the outer carbon coating layer. A portion of the SWCNT body is spaced apart from the outer carbon coating layer, thereby forming a conductive network between the composite anode active materials. Accordingly, in the composite anode active material of the present invention, even if the silicon-based core particles expand in volume due to charging and discharging, an electrical short circuit can be prevented due to the formation of a conductive network of the single-walled carbon nanotubes, and the lifespan characteristics and resistance of the anode are reduced preferred in [39] In addition, according to the present invention, since the SWCNTs are in contact with the outer carbon coating layer, when the composite negative active material is included in the negative electrode, the SWCNTs can be uniformly disposed in the negative electrode, thereby forming a uniform and stable conductive network in the negative electrode do. [40] [41] The silicon-based core particle is capable of insertion/desorption of lithium, and may function as a core particle of the composite anode active material. [42] The silicon-based core particle may include a compound represented by Formula 1 below. [43] [Formula 1] [44] M x SiO y [45] In Formula 1, M is at least one selected from the group consisting of Li, Mg, and Al, and may be 0≤x≤4, and 0≤y<2. [46] In Formula 1, SiO 2 (when x=0 and y=2 in Formula 1) does not react with lithium ions and cannot store lithium, so y is preferably within the above range. Specifically, y may be 0.5≤y≤1.5 in terms of structural stability of the active material in Formula 1 above. [47] In Formula 1, M may be contained in terms of increasing the efficiency of the active material by lowering the ratio of the irreversible phase (eg, SiO 2 ) of the silicon-based core particle, and at least selected from the group consisting of Li, Mg and Al. It may be one type, and preferably may be at least one type selected from the group consisting of Li and Mg. [48] The average particle diameter (D 50 ) of the silicon-based core particles contributes to structural stability of the active material during charging and discharging, and can better maintain electrical contact when used in combination with SWCNTs, and volume expansion/contraction as the particle size becomes excessively large It may be 1 μm to 10 μm, preferably 2 μm to 6 μm, in terms of preventing the problem of increasing the level and preventing the problem of reducing the initial efficiency due to an excessively low particle size. [49] The silicon-based core particles may be included in the composite negative active material in an amount of 90 wt% to 99.9 wt%, preferably 92 wt% to 97 wt%. When it is in the above range, it is preferable in terms of capacity improvement of the negative electrode, and since the conductive network formed by SWCNT, which will be described later, can be formed at a smooth level, it is preferable to prevent electrical short circuit due to volume expansion of the active material and improve lifespan characteristics. [50] [51] The outer carbon coating layer is formed on the silicon-based core particles, so that volume expansion/contraction by charging and discharging of the silicon-based core particles is appropriately controlled, and the SWCNTs are partially attached to make them complex with the SWCNTs. [52] The outer carbon coating layer contains oxygen (O), and the oxygen is contained in an amount of 35 wt% to 55 wt% in the outer carbon coating layer. [53] The outer carbon coating layer may be formed by mixing silicon-based core particles, SWCNTs, and a precursor for forming an outer carbon coating layer and heat-treating, and oxygen in the precursor for forming the outer carbon coating layer may be reduced by the heat treatment. The composite anode active material of the present invention includes an outer carbon coating layer whose oxygen content is controlled within the range by heat treatment to an appropriate level, so that a portion of the SWCNT body exposed to the outside while spaced apart from the outer carbon coating layer forms a conductive network between the composite anode active materials. It can be made to form more uniformly and stably. [54] When the oxygen content is less than 35% by weight in the outer carbon coating layer, it can be evaluated that the outer carbon coating layer is excessively carbonized by heat treatment, and accordingly, the outer carbon coating layer excessively adsorbs or attaches SWCNTs to the free and flexible conductive network of SWCNTs. Formation can be difficult. When the oxygen content is greater than 55% by weight in the outer carbon coating layer, the level of heat treatment for forming the outer carbon coating layer is not sufficient, so that SWCNTs cannot be fixed at a desirable level in the composite anode active material. [55] The oxygen may be included in the outer carbon coating layer in an amount of preferably 40 wt% to 55 wt%, more preferably 49 wt% to 52 wt%, and when in the above range, a part of the SWCNT body is formed with the outer carbon coating layer and It is preferable because the SWCNT and the outer carbon coating layer can be attached to be spaced apart. [56] The oxygen content may be implemented by selecting a precursor for forming the outer carbon coating layer and controlling the heat treatment temperature. [57] The oxygen content in the outer carbon coating layer may be measured by X-ray photoelectron spectroscopy (XPS). [58] The outer carbon coating layer may be included in the composite anode active material in an amount of 0.001 wt% to 0.2 wt%, preferably 0.01 wt% to 0.1 wt%, more preferably 0.05 wt% to 0.078 wt%, in the above range SWCNT It is preferable that the SWCNTs can be sufficiently attached to the outer carbon coating layer so that a portion of the body of the body is spaced apart from the outer carbon coating layer. [59] [60] The SWCNT is in contact with the outer carbon coating layer, but a portion of the body of the single-walled carbon nanotube is spaced apart from the outer carbon coating layer. The outer carbon coating layer and the SWCNT may be in contact, a portion of the SWCNT body may be spaced apart from the outer carbon coating layer, and the other portion of the SWCNT body may be attached to or adsorbed to the outer carbon coating layer. [61] SWCNT is a type of carbon nanotube having a single cylindrical wall, and has a fiber shape. SWCNT has a long fiber length and has a high graphitization degree and crystallinity as compared to multi-wall carbon nanotubes (MWCNTs), because cutting does not occur during tube growth. [62] In the composite anode active material of the present invention, a part of the SWCNT body may be exposed to the outside while being spaced apart from the outer carbon coating layer, and a part of the SWCNT body exposed to the outside has a long fiber length, flexibility and Due to the high crystallinity, it is possible to form a conductive network that helps electrical contact between the composite anode active materials. Accordingly, in the composite negative active material of the present invention, SWCNTs can stably maintain electrical contact even when the active materials expand in volume due to charging and discharging in the negative electrode. Therefore, the composite anode active material of the present invention can effectively prevent the occurrence of an electrical short due to the volume expansion of the active material and the rapid deterioration of the lifespan of the active material, improve the lifespan characteristics of the anode, and facilitate electrical contact between the active materials due to SWCNT. It is also desirable from the viewpoint of reducing resistance and improving efficiency due to maintenance. [63] In addition, in the composite anode active material of the present invention, since SWCNTs are in contact with the outer carbon coating layer, SWCNTs can be uniformly disposed between active materials compared to a case of simply mixing the active material and SWCNTs, and a uniform and stable conductive network in the anode can be formed [64] The average length of the SWCNTs may be 3 μm or more, preferably 4 μm or more, and more preferably 4.5 μm to 10 μm. When in the above range, it is preferable to smoothly maintain the conductive network between the active materials. [65] In the present specification, the average length of the SWCNTs is measured by the following method. A solution in which SWCNT and carboxymethyl cellulose (CMC) are added to water in a weight ratio of 40:60 (solid content is 1% by weight based on the total weight of the solution) is diluted 1,000-fold in water. Thereafter, 20 ml of the diluted solution is filtered through a filter, and the SWCNT filter is dried. 100 sheets of the dried filter are photographed with a scanning electron microscope (SEM), the SWCNT length is measured using the imageJ program, and the average value of the length is defined as the average length of the SWCNT. [66] The SWCNTs may have an average diameter of 0.1 nm to 15 nm, preferably 2 nm to 7 nm. When the average diameter of the SWCNTs is in the above range, it is preferable in terms of preventing breakage of the SWCNTs and ensuring flexibility. [67] In the present specification, the average diameter of the SWCNTs is measured by the following method. A solution in which SWCNT and carboxymethyl cellulose (CMC) are added to water in a weight ratio of 40:60 (solid content is 1% by weight based on the total weight of the solution) is diluted 1,000-fold in water. Drop 1 drop of the diluted solution on the TEM grid, and dry the TEM grid. The dried TEM grid was observed with TEM equipment (product name: H7650, manufacturer: Hitachi) to measure the average diameter of the SWCNTs. [68] The ratio of the average length of the SWCNTs to the average diameter may be 500:1 or more, preferably 500:1 to 10,000:1, preferably 750:1 to 2,000:1, and when in the above range, SWCNTs have high conductivity It is preferable in terms of having a , breaking phenomenon is prevented and flexibility can be improved. [69] The SWCNT may be included in the composite negative active material in an amount of 0.005 wt% to 0.2 wt%, preferably 0.015 wt% to 0.15 wt%, more preferably 0.05 wt% to 0.12 wt%, and when in the above range, excess SWCNT The addition prevents the SWCNTs from being entangled with each other and aggregation of the active materials together, which is preferable in terms of being able to form a conductive network more uniformly while sufficiently improving electrical conductivity. [70] [71] The composite anode active material of the present invention may further include an internal carbon coating layer formed between the silicon-based core particle and the outer carbon coating layer. The inner coating layer may function as a protective layer that suppresses volume expansion of the silicon-based core particles and prevents side reactions with the electrolyte. [72] The internal carbon coating layer may be included in an amount of 1 wt% to 10 wt%, preferably 3 wt% to 7 wt%, in the composite negative active material, and when the range is in the range, the internal carbon coating layer is excellent in volume expansion of the silicon-based core particles It is preferable in terms of being able to prevent side reactions with the electrolyte while controlling the level. [73] The internal carbon coating layer may be included in an amount of 1 wt% to 10 wt%, preferably 3 wt% to 7 wt%, based on the weight of the silicon-based core particle and the internal carbon coating layer, when the internal carbon coating layer is in the above range It is preferable in terms of preventing side reactions with the electrolyte while controlling the volume expansion of the silicon-based core particles to an excellent level. [74] [75] [76] In addition, the present invention provides a method for preparing the above-described composite negative electrode active material. [77] Specifically, the manufacturing method of the composite negative electrode active material of the present invention comprises the steps of mixing a silicon-based core particle, a precursor for forming an outer outer carbon coating layer, and SWCNT; and heat-treating the mixture at 250°C to 650°C. [78] According to the manufacturing method of the composite anode active material of the present invention, an outer carbon coating layer is formed on the silicon-based core particle by mixing a silicon-based core particle, a precursor for forming an outer outer carbon coating layer, and SWCNTs and heat treatment in a specific temperature range, and the SWCNTs are A composite anode active material in a form in which a portion of the SWCNT body is spaced apart from the outer carbon coating layer may be formed in contact with the outer carbon coating layer. [79] In addition, according to the manufacturing method, the SWCNT and the outer carbon coating layer may be in contact with each other, but a portion of the SWCNT body may be spaced apart from the outer carbon coating layer to be exposed to the outside of the composite negative electrode active material. A portion of the SWCNT body exposed to the outside may form a conductive network that improves electrical contact between composite negative active materials. The other part of the SWCNT body that is not spaced apart from the outer carbon coating layer can be attached and fixed to the outer carbon coating layer, so that the conductive network between the composite anode active materials can exist at a more stable and uniform level. Accordingly, it is possible to effectively prevent the problem of volume expansion due to the use of the silicon-based core particle as an active material, and thus an electrical short circuit and a decrease in lifespan. [80] [81] The method of manufacturing a composite anode active material of the present invention includes mixing silicon-based core particles, a precursor for forming an outer outer carbon coating layer, and SWCNTs. [82] The silicon-based core particles and SWCNT types, characteristics, content, etc. have been described above. [83] The precursor for forming the outer carbon coating layer is a component capable of forming the outer carbon coating layer of the composite anode active material. [84] The precursor for forming the outer carbon coating layer is carboxy methyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl cellulose (HPC), methyl hydroxypropyl cellulose (MHPC) ), ethyl hydroxyethyl cellulose (EHEC), methyl ethyl hydroxyethyl cellulose (methyl ethyl hydroxyethyl cellulose, MEHEC), and may be at least one selected from the group consisting of cellulose gum (cellulose gum), preferably It may be carboxymethylcellulose. [85] [86] The method of manufacturing a composite negative active material of the present invention may further include forming an internal carbon coating layer on the silicon-based core particle before the mixing step. The internal carbon coating layer is formed on the silicon-based core particles, and may function as a protective layer that can appropriately control volume expansion according to charging and discharging of the silicon-based core particles and prevent side reactions with the electrolyte. [87] The step of forming the inner carbon coating layer may be performed by chemical vapor deposition (CVD), specifically, chemical vapor deposition (CVD) using at least one hydrocarbon gas selected from the group consisting of methane, ethane and acetylene. can be performed by According to the method, the internal carbon coating layer can be formed at a uniform level on the silicon-based core particles, so that the volume expansion of the silicon-based core particles can be smoothly controlled, and side reactions caused by the electrolyte can be prevented. [88] The forming of the inner carbon coating layer may be performed at 800°C to 1,100°C, preferably 900°C to 1,000°C. [89] Other descriptions of the inner carbon coating layer have been described above. [90] [91] The method for preparing a composite negative active material of the present invention includes heat-treating the mixture at 250°C to 650°C. [92] If the heat treatment temperature is less than 250° C., the oxygen content in the outer carbon coating layer is excessive, and it is difficult to sufficiently fix the SWCNTs in the carbon coating layer, so that it may be difficult to form a uniform conductive network in the anode. If the heat treatment temperature is higher than 650° C., the carbon coating layer is excessively carbonized or the SWCNTs are attached and fixed in the carbon coating layer more than necessary, and it may be difficult to form a free and flexible conductive network of SWCNTs. [93] Preferably, the heat treatment temperature may be 350 ° C. to 500 ° C., when the oxygen content in the outer carbon coating layer is in the above range, the oxygen content in the outer carbon coating layer can be adjusted to an appropriate level, and the SWCNT can be attached to the outer carbon coating layer while securing the flexibility of the SWCNT. desirable. [94] The heat treatment may be carried out for 0.5 hours to 5 hours, preferably 0.7 hours to 2 hours, and when it is in the above range, the degree of adhesion or adsorption of SWCNTs is controlled to a desired level, and the oxygen content in the outer carbon coating layer is adjusted to an appropriate level. It is preferable in terms of control. [95] According to the manufacturing method of the composite negative electrode active material of the present invention, oxygen in the precursor for forming the outer carbon coating layer is reduced by the heat treatment, and the outer carbon coating layer is formed so that the precursor for forming the outer carbon coating layer attaches and fixes a part of the SWCNTs. can Specifically, the outer carbon coating layer may contain oxygen in an amount of 35 wt% to 55 wt%, preferably 40 wt% to 55 wt%, and more preferably 49 wt% to 52 wt%. When it is in the oxygen content range, it can be determined that the attachment and fixation of a part of SWCNTs in the outer carbon coating layer is properly made. [96] [97] [98] In addition, the present invention provides a negative electrode comprising the above-described composite negative electrode active material. [99] Specifically, the negative electrode of the present invention is a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode material, a binder, and a conductive material, and the negative electrode material includes the above-described composite negative electrode active material. [100] The anode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Specifically, the negative electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, one in which the surface of copper or stainless steel is surface-treated with carbon, nickel, titanium, silver, etc., and an aluminum-cadmium alloy may be used. have. [101] The negative electrode current collector may typically have a thickness of 3 to 500 μm. [102] The negative electrode current collector may form fine concavities and convexities on the surface to strengthen the bonding strength of the negative electrode active material. For example, the negative electrode current collector may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body, and the like. [103] The anode active material layer is formed on the anode current collector. [104] The negative active material layer may include a negative electrode material and a binder, and the negative electrode material includes the above-described composite negative active material. [105] The composite negative active material may be included in the negative electrode to exhibit excellent capacity characteristics, and the SWCNT included therein may contribute to improving the lifespan characteristics of the negative electrode. [106] The description of the composite negative active material has been described above. [107] The negative electrode material may further include a carbon-based active material together with the above-described composite negative active material, and thus the degree of volume expansion of the entire negative electrode material may be lowered by the carbon-based active material having a low degree of volume expansion due to charging and discharging, and the composite The conductive network due to SWCNTs in the negative active material can surround the carbon-based active material, which is more preferable for improving resistance and efficiency. [108] The carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, acetylene black, Ketjen black, super P, graphene, and fibrous carbon, preferably It may include at least one selected from the group consisting of artificial graphite and natural graphite. [109] The average particle diameter (D 50 ) of the carbon-based active material may be 5 μm to 35 μm, preferably 10 μm to 20 μm, in terms of structural stability during charging and discharging and reducing side reactions with the electrolyte. [110] Specifically, the negative electrode material preferably uses both the composite negative electrode active material and the carbon-based active material in terms of simultaneously improving capacity characteristics and cycle characteristics, and specifically, the negative electrode material includes the composite negative electrode active material and the carbon-based active material 5 : 95 to 30:70, preferably 10:90 to 20:80 weight ratio. When it is in the above range, it is preferable in terms of simultaneous improvement of capacity and cycle characteristics. [111] The anode material may be included in the anode active material layer in an amount of 80 wt% to 99 wt%, preferably 90 wt% to 98.5 wt% in the anode active material layer. [112] The negative active material layer includes a binder. [113] The binder further improves electrode adhesion and in terms of providing sufficient resistance to volume expansion/contraction of the active material, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (acrylonitrile butadiene rubber), acrylic rubber (acrylic rubber), butyl rubber, fluoro rubber, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol (PVA: polyvinyl alcohol), It may include at least one selected from the group consisting of polyacrylic acid (PAA), polyethylene glycol (PEG: polyethylene glycol), polyacrylonitrile (PAN: polyacrylonitrile), and polyacryl amide (PAM: polyacryl amide). . Preferably, the binder has high strength, has excellent resistance to volume expansion/contraction of the silicon-based negative active material, and provides excellent flexibility to the binder to prevent distortion and warpage of the electrode. It is preferable to include [114] The binder may be included in the anode active material layer in an amount of 0.5 wt% to 10 wt%, and when it is in the above range, it is preferable in terms of being able to more effectively control the volume expansion of the active material. [115] If necessary, the anode active material layer may further include a conductive material. The conductive material may be used to improve the conductivity of the negative electrode, and it is preferable to have conductivity without causing a chemical change. Specifically, the conductive material is natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, farness black, lamp black, thermal black, conductive fiber, fluorocarbon, aluminum powder, nickel powder, zinc oxide, titanic acid It may be at least one selected from the group consisting of potassium, titanium oxide, and polyphenylene derivatives, and may preferably include carbon black in terms of realizing high conductivity. [116] The conductive material may be included in the negative active material layer in an amount of 0.5 wt% to 10 wt%. [117] The anode active material layer may have a thickness of 30 µm to 100 µm, preferably 40 µm to 80 µm, in terms of increasing electrical contact to components of the anode material due to the aforementioned SWCNT. [118] [119] The negative electrode is prepared by dispersing a negative electrode material, a binder and a conductive material on the negative electrode current collector in a solvent for forming a negative electrode slurry to prepare a negative electrode slurry, coating the negative electrode slurry on the negative electrode current collector, drying and rolling can be [120] The solvent for forming the negative electrode slurry may include at least one selected from the group consisting of distilled water, ethanol, methanol, and isopropyl alcohol, preferably distilled water, in terms of facilitating dispersion of the components. [121] [122] [123] The present invention provides a secondary battery including the above-described negative electrode, specifically, a lithium secondary battery. [124] Specifically, the secondary battery according to the present invention includes the above-described negative electrode; an anode opposite to the cathode; a separator interposed between the negative electrode and the positive electrode; and electrolytes. [125] The positive electrode is a positive electrode current collector; It may include a positive electrode active material layer formed on the positive electrode current collector. [126] The positive electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Specifically, the negative electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, one in which the surface of copper or stainless steel is surface-treated with carbon, nickel, titanium, silver, etc., and an aluminum-cadmium alloy may be used. have. [127] The positive electrode current collector may typically have a thickness of 3 to 500 μm. [128] The positive electrode current collector may form fine concavities and convexities on the surface to strengthen the bonding force of the negative electrode active material. For example, the negative electrode current collector may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body, and the like. [129] The positive active material layer may include a positive active material. [130] The positive active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, a lithium transition metal composite oxide containing lithium and at least one transition metal consisting of nickel, cobalt, manganese and aluminum; Preferably, it may include a lithium transition metal composite oxide containing a transition metal containing nickel, cobalt and manganese and lithium. [131] More specifically, as the lithium transition metal composite oxide, lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4 , etc.), lithium-cobalt-based oxide (eg, LiCoO 2 , etc.), lithium-nickel Oxide-based oxides (eg, LiNiO 2 , etc.), lithium-nickel-manganese oxides (eg, LiNi 1-Y Mn Y O 2 (here, 0 [220] As an anode material, a mixture of the composite anode active material prepared in Example 1 and natural graphite (average particle diameter (D 50 ): 15 μm) as a carbon-based active material in a weight ratio of 15:85 was used. [221] A negative electrode slurry was prepared by mixing the negative electrode material, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose as a thickener in a weight ratio of 98:1:1, and adding this to distilled water as a solvent for forming the negative electrode slurry. [222] As a negative electrode collector, the negative electrode slurry was coated on one side of a copper current collector (thickness: 15 μm) at a loading amount of (3mAh/cm 2 ), rolled, and dried in a vacuum oven at 130° C. for 10 hours. to form a negative active material layer (thickness: 42 μm), which was used as the negative electrode according to Example 1 (thickness of the negative electrode: 57 μm, area 1.4875 cm 2 , circular). [223] [224] In addition, in the same manner as in Example 1, Examples 2 to 4, Comparative Examples 1 to, except that the composite negative active materials of Examples 2 to 4 and Comparative Examples 1 to 5 were used instead of the composite negative active material of Example 1, respectively. A negative electrode of 5 was prepared. [225] [226] [227] A lithium metal thin film having an area of ​​1.7671 cm 2 and having a circular shape was used as the positive electrode. [228] A coin-type half-cell secondary battery was prepared by interposing a separator of porous polyethylene between the anode and the anode prepared above, and injecting an electrolyte. [229] As the electrolyte, in a solution of ethylmethyl carbonate (EMC) and ethylene carbonate (EC) in a volume ratio of 7:3, 0.5 wt% of vinylene carbonate (VC) was dissolved, and LiPF 6 was dissolved at a concentration of 1M. was used. [230] [231] [232] For the secondary batteries prepared in Examples 1 to 4 and Comparative Examples 1 to 5, cycle capacity retention rates were evaluated using an electrochemical charger/discharger. [233] The cycle capacity retention rate was 0.1C in the 1st and 2nd cycles, and charging and discharging at 0.5C from the 3rd cycle (Charging conditions: CC/CV, 5mV/0.005C cut-off, discharge conditions: CC, 1.5V cut off) [234] The capacity retention rate was calculated as follows. [235] Capacity retention rate (%) = {(discharge capacity in Nth cycle)/(discharge capacity in 1st cycle)} × 100 [236] (in Equation 2, N is an integer greater than or equal to 1) [237] The 100th cycle capacity retention rate (%) is shown in Table 2 below. [238] [239] [Table 2] [240] [241] Referring to Table 2, it can be confirmed that the negative electrode and the secondary battery using the composite negative active material of Examples 1 to 4 improved the cycle capacity retention rate to an excellent level compared to Comparative Examples 1 to 5. WE CLAIMS silicon-based core particles; an outer carbon coating layer formed on the silicon-based core particles; and a single-walled carbon nanotube; wherein the single-walled carbon nanotube is in contact with the outer carbon coating layer, wherein a portion of the body of the single-walled carbon nanotube is spaced apart from the outer carbon coating layer, and the outer carbon coating layer A composite negative electrode active material comprising silver oxygen in an amount of 35 wt% to 55 wt% in the outer carbon coating layer. [Claim 2] The method according to claim 1, wherein the silicon-based core particle is a composite negative electrode active material comprising a compound represented by the following formula (1): [Formula 1] M x SiO y In Formula 1, M is at least selected from the group consisting of Li, Mg and Al It is 1 type, 0≤x≤0.4, and 0≤y<2. [Claim 3] The composite anode active material of claim 1 , further comprising an internal carbon coating layer formed between the silicon-based core particle and the outer carbon coating layer. [Claim 4] The composite anode active material of claim 1, wherein the average length of the single-walled carbon nanotubes is 3 μm or more. [Claim 5] The composite anode active material of claim 1 , wherein the average diameter of the single-walled carbon nanotubes is 0.1 nm to 15 nm. [Claim 6] The composite anode active material of claim 1, wherein the single-walled carbon nanotube is included in an amount of 0.005 wt% to 0.2 wt% in the composite anode active material. [Claim 7] mixing silicon-based core particles, a precursor for forming an outer carbon coating layer, and single-walled carbon nanotubes; and heat-treating the mixture at 250°C to 650°C. [Claim 8] The method according to claim 7, wherein the heat treatment is performed for 0.5 to 5 hours. [Claim 9] The method according to claim 7, wherein the precursor for forming the outer carbon coating layer is from the group consisting of carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, methyl hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, methyl ethyl hydroxyethyl cellulose and cellulose gum. A method of manufacturing at least one selected composite anode active material. [Claim 10] The method according to claim 7, further comprising the step of forming an internal carbon coating layer on the silicon-based core particles before the mixing step. [Claim 11] The method of claim 10 , wherein the forming of the internal carbon coating layer is performed by chemical vapor deposition (CVD) using at least one hydrocarbon gas selected from the group consisting of methane, ethane, and acetylene. [Claim 12] negative electrode current collector; and an anode active material layer formed on the anode current collector, wherein the anode active material layer includes an anode material including the composite anode active material according to claim 1, a binder, and a conductive material. [Claim 13] The negative electrode of claim 12 , wherein the negative electrode material further includes a carbon-based active material, and the negative electrode material includes the composite negative active material and the carbon-based active material in a weight ratio of 5:95 to 30:70. [Claim 14] the negative electrode according to claim 12; an anode opposite to the cathode; a separator interposed between the negative electrode and the positive electrode; and an electrolyte; a secondary battery comprising a.